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The World Wide Web

The World Wide Web. A part of the Internet. Developed by a research institute called CERN to share pictures and data. Early browsers include Mosaic. Allowed to grow when the backbones (high bandwidth connections) were allowed to become commercial in the early 90’s. Web Browsers.

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The World Wide Web

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  1. The World Wide Web • A part of the Internet. • Developed by a research institute called CERN to share pictures and data. • Early browsers include Mosaic. • Allowed to grow when the backbones (high bandwidth connections) were allowed to become commercial in the early 90’s.

  2. Web Browsers • Clients connect to servers. • They download data and interpret it. • The data is in (HTML) source code and binary form. • Most are highly configurable. • Can store preferences. • Can store favorite sites.

  3. Examples of Browsers • Text browser – Lynx • Graphical Browsers • Internet Explorer • Netscape Navigator • Mozilla • Opera • Wireless/PDA browsers.

  4. Browsing • You can download and possibly upload • Webpages • Data files • Computer Programs • Music/Sounds • Pictures/Movies • (But don’t steal! People work very hard to make the things you enjoy!)

  5. Browsing 2 • Browsers connect to servers using TCP/IP • Like when I connected to www.umd.edu port 80 using telnet. • They can be used as • Email clients • Newsreaders • Simple webpage makers • File viewers

  6. Redundant Slide • To get this slide, start a browser. • Go to http://www.cs.umd.edu • Click on Class Web Pages. • Click on CMSC102 link at top of page. • Click on Part6. • View the slide in MS Word or Powerpoint. • Then you don’t need to view this slide.

  7. Netiquette • Don’t post or send inflammatory messages. • Everything is (or can be) recorded. • Assume that whatever you type will be around forever. • People use the ‘Net to check up on prospective hires. • So what you type now may haunt you forever.

  8. Netiquette 2 • Flaming – writing rude, obnoxious messages – should be avoided. • Spamming – should be avoided. • Sending useless annoying messages to boards or newsgroups. • sending many pieces unsolicited email. • Avoid off-topic or inappropriate messages. • Things ok in alt.sex.bears but not elsewhere.

  9. Lynx – A Text Browser • Type lynx within a Unix account to use it. • Move around with arrows. • Left/Right are backward/forward keys. • Up/Down move around links in current page. • Go lets you open a new address • Can toggle buttons and enter text. • Can set options/preferences.

  10. Netscape Browser – Menu • File -- open new pages/windows, edit page. • Edit -- Search, edit preference, find in page • View -- See page source, change fonts. • Go -- forward/backward/home • Communicator -- mail, news, AIM, addressbook, bookmarks.

  11. HTML • HTML -- Hypertext Markup Language • Lets you send text. • Contains formatting information. • Can contain pictures, sounds, other things. • Extends presentation beyond text. • Lets you access other information by “linking” to other documents.

  12. Hypertext • HTML is not the only markup language. • TeX/LaTeX for mathematical typesetting. • Example: • Name: John Arras • Credits: 68 • GPA: 2.56 • Housing: Off-Campus • Select name to get John Arras, etc…

  13. URL’s • Uniform Resource locators. • Ex: http://www.umd.edu/classes/index.html • Resource type: http. • Others: telnet, ftp, mailto, gopher, nntp • Host: www.umd.edu • Directory and file: classes/index.html.

  14. Start using Netscape • Some search engines • www.lycos.com • www.yahoo.com • www.google.com • www.overture.com • www.askjeeves.com • Your ISP’s homepage.

  15. Customization • Boomarks -- good sites to remember. • List them • Edit them • Preferences -- change settings • Fonts • Mail/newsgroup settings • Cache/cookies

  16. Interesting sites • www.umd.edu • www.theonion.com • www.washingtonpost.com • www.nasa.gov • www.fark.com • www.slate.com • www.salon.com

  17. Some File Types • .txt -- Plain text file • .html -- html file • .mp3 -- mpeg3 sound (music file) • .wav -- WAVE sound file • .zip -- PKZIP compressed file • .mpg -- MPEG compressed movie • .gif -- Graphics Image Format • .jpg -- JPEG compressed picture

  18. Other features • Plugins or viewers to listen/view different file types. • CGI (Common Gateway Interface) Lets Web servers run programs. • Servers may run Java or other scripts or special HTML codes. • Dynamically generated webpages.

  19. Usability Issues • http://www.otal.umd.edu/UUGuide/ • Blind -- Text vs. graphics. • Lawsuits vs. major companies over this. • Cognitively disabled --Alzheimer’s. • Novice vs. Expert -- Learning Curve. • Low Income -- Access to technology.

  20. Usability Enhancements • Adaptive software, adjusts to the user. • Multiple Bandwidth options. • Online help. • Media conversion -- video to audio.

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